a. a grid, the grid having a plurality of apertures adapted in size and shape to permit fluid to pass through the grid but to block at least some trash;

b. a support structure for mounting the grid within a channel, wherein the support structure is connected to at least one surface of the channel, wherein

the grid is rotatably connected via a rotation means to the support structure and

the grid is rotatable between positions that comprise a closed position and an open position, wherein,

while in the closed position, the grid is positioned to intercept the path of at least some of the trash that is moved by the fluid flowing through the channel, and,

while in the open position, the grid is positioned to permit at least some of the intercepted trash to move downstream from the closed position, and wherein

the support structure comprises a front support;

c. a hold-release means for at least helping to hold the grid in the closed position until an occurence of predetermined release conditions, wherein said hold-release means releasably connects at least part of the grid to the front support and wherein said hold-release means releasably connects at least part of the grid from the front support in response to the occurence of predetermined release conditions, wherein pressure against the upstream side of the grid urges the grid toward the open position; and, wherein the hold-release means automatically releasably re-connects the at least part of the grid to the front support upon return of the grid to the closed position; and,

d. a means for applying torque to the grid in a direction for rotating the grid between the open position and the closed position, said means for applying torque to the grid being comprised of the grid's weight, a torque-inducing means, or both the grid's weight and the torque-inducing means.